Coma is the lack of any awareness of self and environment despite painful or other external stimulation ( Table 31.1 ). Delirium is an alternation in consciousness that falls along the spectrum from normal awareness to coma and is characterized by irritability, agitation, lack of contact with the environment, and confusion. Periods of lucidity may alternate with the delirious state, and patients may proceed rapidly from delirium to lethargy or coma. Any alteration in the level of consciousness whether delirium, lethargy, obtundation, stupor, or coma must be managed as a life-threatening emergency until proven otherwise.
| Coma: A state of unarousable unresponsiveness; even strong exteroceptive stimuli fail to elicit recognizable psychologic responses; unresponsive to pain |
| Stupor: Spontaneous unarousability interruptible only by vigorous, direct external stimulation; responsive only to pain |
| Hypersomnia, pathologic drowsiness, obtundation: Terms applied to an increase above the patient’s normal sleep/wake ratio, often accompanied during wakefulness by reduced attention and interest in the environment; responsive to pain and other stimuli |
| Delirium: An acute or subacute reduction in awareness, attention, orientation, and perception (“clouding of consciousness”), usually fluctuating and accompanied by abnormal sleep/wake patterns and often psychomotor disturbances |
| Syncope: Brief loss of consciousness caused by global failure of cerebrovascular perfusion |
| Dementia: A sustained or permanent multidimensional or global decline in cognitive functions |
| Vegetative state: A sustained, complete loss of cognition, with sleep/wake cycles and other autonomic functions remaining relatively intact; can either follow acute, severe bilateral cerebral damage or develop gradually as the end stage of a progressive dementia |
| Locked-in state: Preservation of intellectual activity accompanied by severe or total incapacity to express voluntary responses as a result of damage to or dysfunction of descending motor pathways in the brain or peripheral motor nerves; most, but not all, such patients can use vertical eye movements to signal by code |
Background
Arousal and awareness form the foundation for normal cognitive function. Arousal is determined in the brainstem’s ascending reticular activating system, and awareness is generated in the cortex. The cortex is the central processing center that interprets neuronal input and generates awareness. Injury to these areas creates an alteration in consciousness. Standardized language is necessary to properly diagnose and treat alterations in consciousness since terms, such as lethargy, obtundation, stupor, and coma, are qualitative descriptions. Rating scales allow different observers to follow the progression of the patient’s mental status over time and facilitate effective communication of clinical information. The most widely used grading system is the Glasgow Coma Scale (GCS) ( Table 31.2 ), which has been modified for children less than 5 years of age based on their age-appropriate developmental abilities ( Table 31.3 ). The GCS was initially intended for use in traumatic injury but has been successfully applied in patients with nontraumatic altered mental status. This 15-point scale evaluates 3 areas of central nervous system (CNS) function: eye opening, verbal response, and motor response. A score of 15 indicates full function, whereas a score of 3 indicates no function. The 1st area of assessment is eye opening, in which the arousability and alertness of the patient are evaluated. Spontaneous eye opening indicates intact arousal mechanisms but does not imply awareness. The 2nd area, verbal response, requires a high degree of integration within the CNS. Oriented responses indicate awareness of person, place, and time. The 3rd area, motor functioning, reflects mentation as well as the integrity of the major CNS pathways. For purposes of gauging global brain function, the best motor response from any limb is taken as the score. Variation in response from one side of the body to the other is indicative of an asymmetric brain lesion. Spinal cord lesions resulting in paralysis or significant orthopedic injuries to the extremities prevent evaluation of the motor portion of the GCS.
| Glasgow Coma Scale (GCS) | Full Outline of Unresponsiveness (FOUR) | ||
|---|---|---|---|
| Eye Opening: | Eye Response: | ||
| 1 | Does not open eyes | 4 | Eyelids open and comply with verbal stimuli |
| 2 | Opens eyes in response to noxious stimuli | 3 | Eyelids open but not tracking |
| 3 | Opens eyes in response to voice | 2 | Eyelids closed but open to loud noise |
| 4 | Opens eyes spontaneously | 1 | Eyelids closed but open to noxious stimuli |
| 0 | Eyelids remain closed | ||
| Verbal Response: | Motor Response: | ||
| 1 | No verbal response | 4 | Thumbs up, fist or peace sign |
| 2 | Incomprehensible sounds | 3 | Localize to pain |
| 3 | Inappropriate words | 2 | Flexion to pain |
| 4 | Confused and disoriented fluid speech | 1 | Extension to pain |
| 5 | Oriented with normal speech | 0 | No response to pain or myoclonus |
| Motor Response: | Brainstem Reflexes: | ||
| 1 | No movements | 4 | Pupil and corneal reflexes present |
| 2 | Extension to noxious stimuli | 3 | One pupil wide and fixed |
| 3 | Flexion to noxious stimuli | 2 | Pupil or corneal reflex absent |
| 4 | Withdrawal to pain | 1 | Pupil and corneal reflexes absent |
| 5 | Localizes to pain | 0 | Absent pupil, corneal, and cough reflex |
| 6 | Obeys commands | ||
| Respirations: | |||
| 4 | Regular breathing pattern | ||
| 3 | Cheyne–Stokes respirations | ||
| 2 | Irregular breathing | ||
| 1 | Intubated but breathing above the vent | ||
| 0 | Breathing at vent rate or apnea | ||
| TOTAL SCORE 3-15 | TOTAL SCORE 0-16 | ||
| Activity | Best Response | Score |
|---|---|---|
| Eye opening | Spontaneously | 4 |
| To speech | 3 | |
| To pain | 2 | |
| None | 1 | |
| Verbal | Oriented | 5 |
| Words | 4 | |
| Vocal sounds | 3 | |
| Cries | 2 | |
| None | 1 | |
| Motor | Obeys commands | 5 |
| Localizes pain | 4 | |
| Flexion to pain | 3 | |
| Extension to pain | 2 | |
| None | 1 | |
| Normal Total Score Based on Age | ||
| Birth–6 mo | 9 | |
| 7-12 mo | 11 | |
| 1-2 yr | 12 | |
| 2-5 yr | 13 | |
| >5 yr | 14 | |
The GCS can provide a general assessment of consciousness but is not intended to take the place of a complete neurologic evaluation ( Table 31.4 ). The scale is an objective measure of the improvement or worsening of the patient’s level of consciousness over time, and interventions are often based on the score. Most patients with traumatic brain injury should undergo endotracheal intubation if their score is 8 or less. Deterioration of a patient’s score by 2 or more points indicates a need for quick re-evaluation of the patient and the possible need for interventions such as endotracheal intubation and diagnostic studies such as a brain computed tomography (CT) scan. The score has been used to assign a prognosis to patients with brain injury, particularly with traumatic brain injury. It may take days to weeks for patients with initial scores of 3-5 to become conscious as opposed to a few days in patients with scores of 6 or higher.
Pupils
Strength
Attempt to Elicit Reflex Posturing
|
The GCS score has also been used as a prognostic indicator in nontraumatic coma. Children presenting after near-drowning with an initial score of 6 or higher have a good outcome. Patients presenting with a score of 5 or less have a high probability of mortality or profound neurologic sequelae, although a patient with a score of 4 or 5 may survive with minimal impairment. A score of 3 on transfer to an intensive care unit after near-drowning has been associated with a nearly 100% rate of poor outcome.
Although the GCS is a widely applied tool for assessment, it does not assess brainstem function and fails to discriminate between low scores and intubated patients. The Full Outline of Unresponsiveness (FOUR) scale is another tool to assess consciousness that has been validated in several different settings with high inter-rater consistency. The FOUR score evaluates eye response, motor response, brainstem reflexes, and respiratory effort on a 4-point scale. The FOUR score eye and motor responses are defined very similar to the GCS (see Table 31.2 ). The assessment of brainstem response focuses on the pupillary and corneal reflexes. The respiratory assessment includes the intubated patient along with respiratory effort. Because the FOUR score includes brainstem responses and not only recognizes but differentiates intubated patients, this scale is better able to discriminate an unresponsive patient with a GCS of 3. In children with nontraumatic impairment of consciousness, using endpoints of mortality and functional outcome, both scales have similar predictive value. Regardless of the scoring system used, reporting the score for each element can increase the precise description of alteration in consciousness in order to make management decisions.
Other scales have been developed to measure the level of consciousness in specific disease states, such as poisonings, and hepatic failure. The Reed classification of coma has been used in the setting of poisoning or intoxication ( Table 31.5 ) and is used to evaluate increasing depths of coma encountered with CNS-depressant drugs. The cardiovascular system is included in this classification because toxic ingestions may depress myocardial contractility or cause vasodilation. Neurologic function in a patient with hepatic encephalopathy is graded according to the scoring system in Table 31.6 .
| Grade 0 * | Asleep Can be aroused Will answer questions |
| Grade 1 * | Comatose Withdraws from painful stimuli Intact reflexes |
| Grade 2 * | Comatose Does not withdraw from painful stimuli No respiratory, circulatory depression Intact reflexes |
| Grade 3 † | Comatose Reflexes absent No respiratory, circulatory depression |
| Grade 4 † | Comatose Reflexes absent Respiratory or circulatory problems |
| Grade 0 | Normal |
| Grade I | Altered spatial orientation, sleep patterns, and affect |
| Grade II | Drowsy but arousable, slurred speech, confusion, and asterixis |
| Grade III | Stuporous but responsive to painful stimuli |
| Grade IV | Unresponsive, with decorticate or decerebrate posturing possible |
Differential Diagnosis
Coma is caused by 1 of 3 etiologies: structural brain disease, diffuse neuronal injury, or to a lesser degree, psychogenic causes. Within these 3 categories, the differential diagnosis of coma in the child is extensive. Excluding traumatic head injuries, broad category causes of altered mental status in children include intracranial infections, hypoxic-ischemic, epilepsy, metabolic encephalopathies, abusive head trauma, toxic ingestion, anatomic abnormalities, and cerebral vascular abnormalities such as emboli or vasculitis ( Table 31.7 ). Some diagnoses (subdural hematoma, hydrocephalus, cerebral edema) may apply to more than 1 category. The age of the patient can help the clinician differentiate the likely causes of coma, although there is considerable overlap ( Table 31.8 ). Patients with delirium must be differentiated from an acute psychotic event ( Table 31.9 ). In addition, in patients who are awake but presenting with an altered mental status, performing an appropriate mental status exam may help evaluate the degree of impairment and potential etiology ( Table 31.10 ). The mental status exam is most abnormal with organic (encephalopathy, encephalitis) causes of altered behavior and mental status.
| Infectious | Metabolic/Systemic | Toxic * | Traumatic * | Anatomic | Hypoxic-Ischemic | Epileptic | Vascular | Psychologic |
|---|---|---|---|---|---|---|---|---|
| Viral | Hypoglycemia * | Sympathomimetics | Concussion * | Tumor | Cardiac arrest | Postictal state * | Embolism | Conversion disorders * |
| Aseptic meningitis * | Inborn errors of metabolism * | Anticholinergics | Cerebral contusion | Hydrocephalus | Cardiac arrhythmia | Status epilepticus * | Spontaneous intraparenchymal hemorrhage | Catatonic schizophrenia |
| Encephalitis * | Hyperammonemia | Phenothiazines | Epidural hematoma | Hydrocephalus with shunt malfunction | Severe shock | Absence status | Subarachnoid hemorrhage | |
| ? Reye syndrome | Hepatic failure | PCP | Subdural hematoma | Subdural hematoma | Near-drowning | Complex partial seizure | Venous sinus thrombosis | |
| ? Hemorrhagic shock and encephalopathy syndrome | Renal diseases | LSD | Epidural hematoma | Neonatal asphyxia * | Vasculitis | |||
| Postinfectious encephalomyelitis | Uremic encephalopathy | Marijuana | Brainstem | Brain abscess | Hypoxemic respiratory failure | Lupus erythematosus | ||
| Hypertensive encephalopathy | Cocaine | Epidural contusion | Subdural empyema | Carbon monoxide poisoning | Hypertensive encephalopathy | |||
| Systemic infection with shock | Dialysis encephalopathy (dysequilibrium syndrome) | Heavy metals (lead) | Diffuse axonal shear injury | Epidural empyema | Cyanide toxicity | Acute confusional migraine * | ||
| Bacterial | Hyperosmolar states | Salicylates | Cerebral edema | Anaphylaxis | ||||
| Meningitis * | Hypernatremia | Organophosphates and carbamates | Cerebral edema * | Intracranial hemorrhage | Asthma | |||
| Brain abscess | Hyperglycemia–diabetes mellitus * | Antihistamines | Intraparenchymal hemorrhage | Cerebrovascular accident | ||||
| Epidural empyema | Hypo-osmolar states | Industrial solvents (inhaled) | Intraventricular hemorrhage (neonate) * | |||||
| Subdural empyema | Hyponatremia * | Alcohols | Obstructive hydrocephalus | |||||
| Systemic infection with shock | Rapid decrease in osmolality in hyperosmolar states | Narcotics | Posttraumatic seizure | |||||
| Toxic shock syndrome | Endocrine disorders | Sedative-hypnotics | Fat embolism | |||||
| Rickettsial infection | Adrenal insufficiency | Barbiturates | ||||||
| Fungal | Hyperthyroidism and hypothyroidism | Carbon monoxide | ||||||
| Fungal meningitis | Hypoparathyroidism | Tricyclic antidepressants | ||||||
| Fungal brain abscess | Mineral abnormalities | Carbamazepine | ||||||
| Protozoan | Hypercalcemia | Cyanide | ||||||
| Meningitis | Hypocalcemia | Methaqualone | ||||||
| Abscess | Hypermagnesemia | Burn encephalopathy | ||||||
| Postimmunization encephalopathy | Hypomagnesemia | |||||||
| Hypophosphatemia | ||||||||
| Hypercapnia | ||||||||
| Hypoxia * | ||||||||
| Shock * | ||||||||
| Vitamin deficiency and dependency states | ||||||||
| Nicotinic acid | ||||||||
| Pantothenic acid | ||||||||
| Pyridoxine | ||||||||
| Thiamine | ||||||||
| Vitamin B 12 | ||||||||
| Intussusception encephalopathy | ||||||||
| Methemoglobinemia | ||||||||
| Acidosis | ||||||||
| Alkalosis | ||||||||
| Porphyria | ||||||||
| Reye syndrome | ||||||||
| ? Hemorrhagic shock and encephalopathy syndrome | ||||||||
| Mitochondrial encephalopathies |
| Neonate | Infant | Child | Adolescent |
|---|---|---|---|
| Hypoglycemia | Meningitis | Meningitis | Meningitis |
| Birth asphyxia | Bacterial | Bacterial | Bacterial |
| Congenital anomalies of the central nervous system | Viral | Viral | Viral |
| Systemic infection with shock | Trauma | Encephalitis | Encephalitis |
| Cardiogenic shock | Abuse/shaken baby syndrome | Trauma | Intentional ingestion |
| Congenital infection | Asphyxia | Ingestion | Recreational drug/alcohol use |
| Bacterial meningitis | Apparent life-threatening event | Reye syndrome | Suicide gesture or attempt |
| Inborn errors of metabolism | Intentional suffocation | Systemic infection with shock | Often involves multiple agents |
| Hypocalcemia | Systemic infection with shock | Seizure | Trauma |
| Intraventricular hemorrhage | Ingestion | Near-drowning | Seizures |
| Seizures | Inborn errors of metabolism | Hypoglycemia | Diabetic ketoacidosis |
| Birth trauma | Hypoglycemia | Intussusception | Systemic infection with shock |
| Hyponatremia | encephalopathy | Toxic shock syndrome | |
| Hypocalcemia | Diabetic ketoacidosis | Reye syndrome | |
| Encephalitis | Spontaneous intracranial hemorrhage | ||
| Postimmunization encephalopathy | Psychologic | ||
| Hemorrhagic shock and encephalopathy syndrome | Lupus | ||
| Intussusception encephalopathy | |||
| Seizures |
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